World Wide Web (WWW) generally comprises a multitude of computer servers having respective databases and a network by which client computing devices can communicate with the computer servers and request and load data. The client device typically uses a “web browser” program to request data, such as web pages, from remote computer servers. Whenever a web browser associated with a client device requests a web page, either by a user specifying a Uniform Resource Locator (URL) or selecting a link in another web page, the web browser locates the server that stores the requested web page and loads the web page into the client device in the form of a HyperText Markup Language (HTML) file. The HTML file may comprise a specification of each component of the web page, such as HTML or Java code, text, graphics, embedded multimedia, links to other web page, etc. Web pages received by the browser may be stored or cached in a memory of the client device and displayed to the user.
Caching of web pages on the client device has number of advantages. It improves an overall access speed to the web page at the client device, because the browser may access the data associated with the web page directly from the client device (e.g., a browser cache), rather than re-requesting the page data from the server. In addition, caching of web pages may allow a user to repeatedly view information within a period of time without retrieving the web pages from the server each time. Moreover, caching of web pages allows an off-line viewing of the cached web pages by the user when a network connection to the server is not available.
Offline browsing of locally saved copies of web pages that have previously been downloaded while in the online state may be useful when the client device is offline or connection to the Internet is unavailable or very slow. Generally, the web pages are downloaded implicitly into a web browser cache as a result of prior online browsing by the user. Alternatively, the web pages may be downloaded into the browser cache explicitly by a web browser configured to keep local copies of certain web pages, which are updated when the web browser is in the online state, either by updating the local copies at regular intervals or by updating the local copies whenever the web browser is switched to the online state. For example, wireless communications devices such as cellular phones, personal digital assistants, handheld computers may provide a user with services such as stock trading, buying or selling goods, and getting sports or flight information. However, the user may not be able to obtain a network connection due to the user being outside a service area of the communications provider's network, being inside a building blocking the transmission and receipt of radio waves, or being out of the range of a relay device that relays information received from the device to the communications provider's network. Using a web browser that is capable of being explicitly configured to download web pages for offline browsing such as the Internet Explorer, the user may be able to bookmark certain web pages (e.g., adding these web pages to a “Favorites” list) for offline browsing to avoid costs, delays and network access problems associated with online or live browsing.
When web pages are bookmarked and saved for offline browsing, the web browser may download to the browser cache copies both the marked web page and, optionally, the associated web contents including hyperlinks with reference to various code, text, graphics, multimedia, etc. However, when the user wishes to browse a web page which was previously visited and saved in the browser cache, it is uncertain whether the saved information of the web page includes all of the associated web page contents and whether linked web contents can be retrieved accurately in a timely manner. For example, due to modified or deleted web content, an error message may be displayed when the hyperlink which points to the web content is selected. It will become increasingly problematic as to the integrity of the saved web page contents of one or more specific web pages for offline browsing when various linked web contents developed by uncoordinated and undisciplined data sources grow, evolve and are subsequently saved and modified in the browser cache over time. It is, therefore, desirable to facilitate effective logical organization and management of a web browser cache, such that the cache may efficiently maintain various linked web page contents for offline browsing.